Many advances are being made in the development of devices and techniques for providing effective medical responses to a variety of heart disorders or arrhythmias. Recent efforts have resulted in the development of implantable cardioverting and pacing devices. One example of such a cardioverting device is disclosed in U.S. Pat. No. 3,952,750 to Mirowski et al.
Despite recent advances there is still room for improvement in this field of implantable devices. There has been an increasing recognition of the need for a device which provides comprehensive automatic control of various cardiac arrhythmias, including ventricular bradycardia, ventricular tachycardia, and ventricular fibrillation.
U.S. Pat. No. 3,857,398 to Rubin is typical of the prior art. It discloses an implantable device which combines pacemaker and defibrillation functions. The device utilizes separate circuitries in dealing with the different functions of pacing and defibrillation. Rubin makes no mention of changing the energy of the pacing pulses. All pacing pulses apparently have the same energy.
U.S. Pat. No. 4,181,133 to Kolenik et. al. discloses an apparatus which provides cardiac pacing and tachycardia break-up pulses. At the onset of tachycardia, the tachycardia pacing pulses are generated and delivered through an output circuit utilized commonly with demand pacer circuitry. Thus, the tachycardia pacing pulses are programmed with the same pulse width and amplitude as the bradycardia pacing pulses.